JP6432740B2 - Medical screw - Google Patents

Description

The present invention relates to a medical screw for joining fracture sites.

  Patent Document 1 discloses a medical screw 1 having a hollow portion called a cannulated screw as shown in FIG. The screw 1 has been conventionally used for joining fracture sites in the medical field. A screw thread portion 1b is formed on the outer surface of the distal end portion 1a, and a conical blade 1c is formed at the foremost end thereof. A through hole 1d is provided as a hollow portion extending along the central axis.

  At the entrance of the through hole 1d of the head 1e of the screw 1, for example, a rotation operation portion 1f made of a hexagonal recess is provided, and a screw-like rotation operation jig whose tip is a hexagon wrench is provided on the rotation operation portion 1f. By inserting and rotating the distal end portion, the screw screw portion 1b is screwed into the bone to join the fracture site.

  As shown in FIG. 11, the conventional screw 1 is screwed into the bone through a skin A and a subcutaneous tissue B in which a metal guide pin 2 is incised under anesthesia. In contrast, it is inserted so as to be substantially orthogonal. The tip of the guide pin 2 is pointed like a cone, and punctures the skin A and the subcutaneous tissue B as they are and comes into contact with the bone cortical surface E of the bone C. I will screw it in.

  Next, the upper end of the guide pin 2 is inserted into the through hole 1 d on the distal end portion 1 a side of the screw 1, and the screw 1 is pushed in while being guided along the guide pin 2. The upper end of the guide pin 2 protruding further upward from the head 1 e of the screw 1 is inserted into the through hole 3 b of the rotation operation jig 3. Subsequently, as shown in FIG. 12, after the screw 1 is pushed into the skin A and the subcutaneous tissue B by the rotation operation jig 3, and the tip 1a of the screw 1 comes into contact with the bone cortex surface E, the rotation operation jig is used. 3 is rotated clockwise by manual operation with the gripping part 3c. With the rotation of the screw 1, the screw screw portion 1b is screwed into the bone C along the guide pin 2 while excavating the bone C with the conical blade 1c at the tip. The screw 1 may be screwed in by a rotation operation jig 3 such as a medical electric drill.

  By screwing the screw 1 into the bone C while observing the X-ray television monitor by X-ray fluoroscopy, the screw screw portion 1b penetrates the fracture site D and starts joining. Then, as shown in FIG. 13, when the head 1 e of the screw 1 reaches the bone cortical surface E, the fracture site D is fixed by the screw 1.

  The rotation operation jig 3 is pulled out from the guide pin 2, and finally the guide pin 2 is pulled out from the bone C, the skin A and the like are sutured, and the joining process by the screw 1 of the fracture site D is completed.

  When several months have passed since the joining process, the fracture site D is healed, so that the process of removing the screw 1 that has finished its role is performed. After incising the skin A and the subcutaneous tissue B, the distal end portion 3a of the rotation operation jig 3 is fitted into the rotation operation portion 1f of the screw 1 and rotated counterclockwise so that the screw screw portion 1b is screwed. Loosen and remove from bone C. In this case, it is preferable to insert an extraction guide pin into the screw 1 and guide the rotary operation jig 3 to the head 1 e of the screw 1.

  After correctly fitting the rotation operation jig 3 to the rotation operation portion 1f, the screw screw portion 1b of the screw 1 comes out of the bone C by rotating counterclockwise. In this withdrawal, the screw 1 is lifted upward by the reaction force of the bone C until the screw screw portion 1b screwed into the bone C reaches the bone cortical surface E. However, when the screw 1 is still buried in the subcutaneous tissue B, the screw screw portion 1b is idled and it is difficult to pull out the screw 1.

  In addition, when the screw 1 is removed from the bone C when the screw 1 is screwed into the fracture site D and is screwed into the subcutaneous tissue B, the screw 1 is temporarily turned on for re-screwing. It is necessary to extract the screw 1. At this time, even if the screw 1 is rotated counterclockwise, the screw thread portion 1b is idled and the screw 1 cannot be pulled out.

  Further, when several months have passed since the joining process, a rejection reaction to the metal occurs in the screwed bone C, and a gap may be formed between the bone C and the screw 1. Also in this case, even if the screw 1 is rotated, the screw thread portion 1b is idled and it becomes difficult to pull out.

  FIG. 21 of Patent Document 2 discloses an orthopedic screw having a function equivalent to that of the medical screw 1, and a reverse internal screw that is opposite to the screw screw at the tip portion inside the head of the orthopedic screw. It is described that a pulling operation jig is screwed onto the reverse inner thread portion and the screw is pulled out while rotating in the reverse screw direction.

  By using this orthopedic screw, by rotating the operating jig in the reverse direction, the extracting operating jig is integrated with the orthopedic screw via the reverse inner screw portion, and the screw screw is loosened from the bone. Can be pulled out easily.

JP 10-272142 A Special table 2011-500215 gazette

  However, since the reverse internal thread portion of the orthopedic screw of this cited reference 2 is formed inside the screw head, if a foreign object such as a callus sticks in the head, the foreign object is not removed. There are drawbacks that cannot be made to function. The removal of this foreign matter is extremely troublesome, and as long as the foreign matter remains in the head, the removal operation jig cannot be properly screwed into the reverse threaded portion, so the foreign matter must be completely removed from the head. However, it becomes a big problem under surgery that requires quickness.

  Moreover, when pulling out the screw of the cited documents 1 and 2, the operating tool for extraction is inserted into the head of the screw and pulled out, but when a force is applied in the lateral direction with respect to the pushing direction of the operating tool. The screw may break. In particular, the screw is often made of titanium, and when a force is applied in the lateral direction, the screw often breaks before bending. Thus, if the screw breaks, in order to take out the screw remaining in the bone, it is necessary to grasp the broken part with a radio pliers-like jig and remove it while turning it, and it must be difficult to remove it. .

The object of the present invention is to provide a medical screw that can solve the above-mentioned problems and can be easily and quickly removed from the bone by using a reverse internal screw formed on the inner periphery of the distal end even when it is broken in the middle. It is in.

In order to achieve the above object, a medical screw according to the present invention is a medical screw made of a metal material for joining fracture sites, and a screw screw portion is formed on the outer surface of the distal end portion of a tubular screw body. A rotation operation part for screwing is provided at the head formed at the rear end of the screw body, and a hollow part is formed from the head of the screw body toward the distal end. An internal thread portion having a reverse screw direction to the screw thread portion is formed only on the inner periphery of the portion.

According to the medical screw according to the present invention, since the inner screw portion engraved in the direction opposite to the screw screw portion is provided on the inner periphery of the distal end portion of the medical screw , even if the medical screw is broken in the middle, It can be easily removed using the threaded portion. Further, at the time of extraction, the external thread portion provided in the reverse screw direction of the extraction operation jig is screwed to the internal screw portion provided on the inner periphery of the tip portion. As a result, the medical screw and the extraction jig are integrated, and the medical screw is loosened by further rotation in the reverse screw direction opposite to the screwing direction of the medical screw, and is easily and quickly pulled out of the body. It becomes possible.

It is a side view of the medical screw of an Example. It is sectional drawing. It is a perspective view of a screwing operation jig. It is explanatory drawing of the state which screwed the medical screw in the fracture site | part. It is explanatory drawing of the state by which the callus is formed in the vicinity of the head. It is principal part sectional drawing of an extraction operation jig. It is explanatory drawing of the state which inserts an extraction operation jig. It is explanatory drawing of the state which extracts a medical screw from the inside of a bone. It is sectional drawing of the medical screw of a modification. It is a perspective sectional view of the conventional medical screw. It is explanatory drawing of the state which inserted the guide pin in the fracture site | part. It is explanatory drawing of the state which inserted the conventional medical screw in the subcutaneous tissue. It is explanatory drawing of the state which screwed in the conventional medical screw in the fracture site | part.

The present invention will be described in detail based on the embodiment shown in FIGS.
FIG. 1 is a side view of the medical screw 11 of the embodiment, and FIG. 2 is a cross-sectional view. A screw thread portion 11b of a right-hand thread is formed on the outer surface of the distal end portion of the body portion 11a of the screw 11, which is a tubular screw body made of a metal material such as titanium, and a conical blade 11c is formed at the forefront thereof. Is provided.

  Further, a head portion 11d is provided at the rear end portion, and a rotation operation that is operated by fitting the tip portion of a screwing operation jig of a hexagon wrench, which will be described later, at the center of the top surface of the head portion 11d. A portion 11e is formed. A hollow portion 11f having a predetermined diameter along the central axis is provided from the head 11d of the screw 11 toward the distal direction.

  A reverse inner screw portion 11g is engraved as a left-hand screw in the reverse screw direction with respect to the screw screw portion 11b inside the screw screw portion 11b at the tip of the hollow portion 11f. Furthermore, a circular insertion hole 11h for inserting a guide pin is provided from the tip of the reverse inner thread portion 11g to the conical blade 11c of the screw 11. In addition, you may make it engrave the reverse internal thread part 11g to the cone blade 11c, without providing the insertion hole 11h for guide pin insertion.

  The total length of the screw 11 is, for example, about 30 to 60 mm, but a plurality of types having different lengths and thicknesses are prepared, and they are properly used depending on the size of the fractured part such as the phalange and the femur and the fracture location. It is desirable.

  FIG. 3 shows a perspective view of the screwing operation jig 12, the tip end portion 12 a is attached to the grip portion 12 c via the shaft portion 12 b, and the tip end portion 12 a is fitted to the rotation operation portion 11 e of the screw 11. Hexagonal wrench. The screwing operation jig 12 is not limited to a hexagon wrench but may be of other types, but the rotation operation part 11e of the screw 11 needs to be of the same type. An insertion hole 12d having a circular cross section is provided from the leading end 12a of the screwing operation jig 12 to the gripping portion 12c at the rear end. The inner diameter of the insertion hole 12d is substantially the same as the inner diameter of the insertion hole 11h of the screw 11, so that a guide pin can be inserted.

  When the screw 11 is screwed into the bone C, the skin A or the like is incised, and the guide pin 2 inserted into the bone C as shown in FIG. 4 is inserted into the insertion hole 11h, the hollow portion 11f and the screw 11 of the screw 11. It passes through the insertion hole 12d of the penetration operation jig 12. In this state, the distal end portion 12 a of the screwing operation jig 12 is fitted to the rotation operation portion 11 e of the screw 11 while being guided by the guide pins 2. Then, by rotating the screwing operation jig 12 manually or electrically in the clockwise clockwise direction, the conical blade 11c of the screw 11 excavates the bone C, and the screw screw portion 11b twists into the bone C. Then, the fracture site D is joined by screwing until the head 11d reaches the bone cortical surface E. Thereafter, the screwing operation jig 12 is removed from the guide pin 2, the guide pin 2 is further removed from the bone C, the skin A and the like are sutured, and the joining by the screw 11 is completed.

  When the broken part D is healed after several months and the screw 11 that is no longer needed is taken out, it is necessary to incise the skin A and pass the extraction operation jig and screw 11 described later through the subcutaneous tissue B and the skin A. is there. However, since the skin A and the subcutaneous tissue B are stretched to some extent, the skin A and the subcutaneous tissue B above the head 11d may be cut into an outer diameter of about 4 mm.

  Further, as time passes, a callus F is formed near the head 11d of the screw 11 as time passes, and the head 11d may be buried in the callus F. In this case, the callus F around the head 11d is peeled off as necessary.

  FIG. 6 is a cross-sectional view of the main part of the removal operation jig 13. The extraction operation jig 13 is provided with a reverse outer screw portion 13a on the outer end at the front end of a shaft portion 13b made of a rod-like body, and the reverse outer screw portion 13a is screwed with the reverse inner screw portion 11g of the screw 11 and screwed. To match.

  Further, an insertion hole 13d for inserting the extraction guide pin 2 'is formed in the central portion of the shaft portion 13b and the gripping portion 13c of the extraction operation jig 13. Furthermore, in order to insert the shaft part 13b along the hollow part 11f of the screw 11, it is often smaller or sufficiently smaller than the inner diameter of the hollow part 11f.

  As shown in FIG. 7, skin A or the like is incised, and is inserted into bone C through hollow portion 11f of screw 11 in which extraction guide pin 2 'is embedded, reverse inner screw portion 11g, and insertion hole 11h. In this case, in the screw 11, if the boundary between the hollow portion 11f and the reverse inner screw portion 11g is tapered, the extraction guide pin 2 'can be smoothly guided to the insertion hole 11h. Next, the upper end of the removal guide pin 2 ′ is inserted into the insertion hole 13 d of the removal operation jig 13. By lowering the extraction operation jig 13 along the extraction guide pin 2 ′, the reverse outer screw portion 13 a of the extraction operation jig 13 is guided to the head 11 d of the screw 11 and further inserted to reverse the front end portion. The outer screw portion 13a is brought into contact with the reverse inner screw portion 11g.

  Thereafter, the extraction operation jig 13 is rotated counterclockwise by the gripping portion 13c, that is, the reverse screw direction, and the reverse outer screw portion 13a of the extraction operation jig 13 is sufficiently twisted to the reverse inner screw portion 11g of the screw 11. When it is inserted, the rotation stops when the tip of the reverse screw portion 11g reaches the boundary between the reverse inner screw portion 11g of the screw 11 and the insertion hole 11h, or the shaft portion 13b of the removal operation jig 13 is turned into the reverse inner screw portion. When it reaches 11 g, the rotation stops, and the removal operation jig 13 is integrated with the screw 11.

  Subsequent to this integration, when the extraction operation jig 13 is further rotated counterclockwise, as shown in FIG. 8, the screw 11 of the screw 11 can be unscrewed into the bone C and taken out. . Even if the screw 11 comes out of the bone C and idles, the screw 11 is integrated with the extraction operation jig 13. Therefore, if the extraction operation jig 13 is pulled up as it is, the screw 11 can be pulled out of the body. Finally, the extraction guide pin 2 ′ is extracted from the bone C, and the skin A and the like are sutured to complete the extraction of the screw 11.

  Although a cavity remains in the bone C after the screw 11 is taken out, the cavity is filled with the bone C over time.

  Further, when an excessive force is applied in the lateral direction when the screw 11 is screwed into the bone C by the operation jig 12 shown in FIG. 4, the screw 11 is broken at the trunk portion 11a. There is. For other reasons as well, only the front portion including the screw screw portion 11b may remain in the bone C. Even in such a case, the removal operation jig 13 and the tip of the screw 11 as described above. By integrating the reverse inner screw portion 11g formed on the inner periphery of the portion, the front portion of the screw 11 can be extracted out of the body.

  In addition, since the location where the extraction operation jig 13 and the reverse inner thread portion 11g of the screw 11 are integrated is on the front end side of the screw 11, the conventional integration location is provided on the screw provided at the rear end. The screw 11 can be reliably extracted without being broken or bent from the body 11a during the extraction operation.

  In the above-described embodiment, the screw thread portion 11b of the screw 11 has been described as a right-hand thread and the reverse inner thread portion 11g has been described as a left-hand thread, but this relationship may be reversed.

  Although the guide pin 2 and the extraction guide pin 2 'have been described as separate members, the same members may be used, and these are not necessarily indispensable members.

  Further, when the guide pin 2 and the extraction guide pin 2 ′ are not used, the insertion hole 11h of the screwing operation jig 12 is not provided without providing the insertion hole 11h of the screw 11 as in the modification shown in FIG. 12d and the insertion hole 13d of the removal operation jig 13 are also unnecessary.

2, 2 'guide pin 11 medical screw 11a trunk 11b screw screw part 11c conical blade 11d head 11e rotation operation part 11f hollow part 11g reverse inner screw part 11h insertion hole 12 screwing operation jig 12a tip part 12d insertion Hole 13 Removal operation jig 13a Reverse external thread part 13b Shaft part 13c Gripping part 13d Insertion hole

Claims (5)

In a medical screw made of a metal material for joining fracture sites, a screw screw portion is formed on the outer surface of the distal end portion of a tubular screw main body, and a screw is formed on the head formed on the rear end portion of the screw main body. A rotation operation part is provided for penetration, a hollow part is formed from the head of the screw body toward the tip, and the inner part of the hollow part has a reverse screw direction with respect to the screw thread part only at the inner periphery of the tip part. A medical screw characterized by forming a screw part.   The medical screw according to claim 1, wherein the inner screw portion is formed inside the screw screw portion.   The medical screw according to claim 1 or 2, wherein an insertion hole for inserting a guide pin is provided from the inner screw portion to the forefront of the screw main body.   The medical screw according to claim 3, wherein an inner diameter of the insertion hole is smaller than an inner diameter of the hollow portion.   The medical screw according to any one of claims 1 to 4, wherein the screw thread portion is a right-hand thread and the inner thread portion is a left-hand thread.

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